Unhappy and dissapointed

My mistake was to take a contract with MTN, some time last year I called to get a policy schedule, till to date I don’t have it..then I called some other time back regarding my account still no assistance. I called back again today for assistance with my account and Im told the information Im asking for they don’t have it, it’s no longer on the system. Mind due I took this contract last year February, so how is it possible that a big company like MTN no longer has my phone’s information on their system, it has not even been 5 years but they no longer have the information. I’m so disappointed at MTN, I feel ****med. I spoke to two consultants today already, forgot the first’s lady name but second time I spoke to Kevin. So who should I go to if they don’t have the information. Im so disappointed and very much unhappy.